Two reflected beams of a slightly divergent ultrasonic Gaussian beam on a water-glass interface are observed and recorded by a Schlieren system. The lateral displacements of the two reflected beams are measured for in...Two reflected beams of a slightly divergent ultrasonic Gaussian beam on a water-glass interface are observed and recorded by a Schlieren system. The lateral displacements of the two reflected beams are measured for incident angle θi in a wide range of 10° around the Rayleigh angle θc. The displacements decrease as the incident angle increases, which is different from the previous predictions for bounded plane-wave beams, where the displacements have extremum at the Rayleigh angle θc.The explanation is based on the fact that the Gaussian beam generated by an ultrasonic transducer with a button (or strip) back electrode is actually slightly divergent. We extend Bertoni and Tamir's theory (Appl. Phys. 2 (1973) 157) to this case, and our calculated curves of the displacements against the incident angle are in agreement with the experimental results for |θi - θc| < 2°.展开更多
The reflected fields of a slightly divergent ultrasonic beam on aliquid-solid interface are recorded by a Schlieren system, and the lateral beam displacements on the interface are measured. The range of the incident a...The reflected fields of a slightly divergent ultrasonic beam on aliquid-solid interface are recorded by a Schlieren system, and the lateral beam displacements on the interface are measured. The range of the incident angle θi is ±5° around the Rayleigh angle θc. The displacements Δ are found to decrease as the incident angle increases. Theoretical calculation reveals that the displacements decrease with the increase in the incident angle for a divergent incident beam, but increase with that for a convergent one. The calculated curve of Δ-θi are in agreement with the experimental results.展开更多
基金the National Natural Science Foundation of China under Grant No.19604008.
文摘Two reflected beams of a slightly divergent ultrasonic Gaussian beam on a water-glass interface are observed and recorded by a Schlieren system. The lateral displacements of the two reflected beams are measured for incident angle θi in a wide range of 10° around the Rayleigh angle θc. The displacements decrease as the incident angle increases, which is different from the previous predictions for bounded plane-wave beams, where the displacements have extremum at the Rayleigh angle θc.The explanation is based on the fact that the Gaussian beam generated by an ultrasonic transducer with a button (or strip) back electrode is actually slightly divergent. We extend Bertoni and Tamir's theory (Appl. Phys. 2 (1973) 157) to this case, and our calculated curves of the displacements against the incident angle are in agreement with the experimental results for |θi - θc| < 2°.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 19604008) .
文摘The reflected fields of a slightly divergent ultrasonic beam on aliquid-solid interface are recorded by a Schlieren system, and the lateral beam displacements on the interface are measured. The range of the incident angle θi is ±5° around the Rayleigh angle θc. The displacements Δ are found to decrease as the incident angle increases. Theoretical calculation reveals that the displacements decrease with the increase in the incident angle for a divergent incident beam, but increase with that for a convergent one. The calculated curve of Δ-θi are in agreement with the experimental results.
